Flow Sensor System Including Transmissive Connection

ABSTRACT

A flow sensor sub-assembly includes a flow tube having a lumen, an outside diameter, a first end, and a second end. An inlet fitting includes a conical orifice sized for insertion in either end of the flow tube, such that an internal passage of the inlet fitting is coaxial and concentric with the lumen and the end of the flow tube abuts a shoulder. An outlet fitting includes a conical orifice sized for insertion in either end of the flow tube, such that an internal passage of the inlet fitting is coaxial and concentric with the lumen and the end of the flow tube abuts a shoulder. A first piezo element integrated with the inlet fitting is arranged at an upstream position of the flow tube assembly and a second piezo element integrated with the outlet fitting is arranged at a downstream position of the flow tube assembly.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/967,996, filed May 1, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/247,204, filed Aug. 25, 2016 (now U.S. Pat. No.9,983,034), which claims the benefit of U.S. Provisional PatentApplication No. 62/211,108, filed Aug. 28, 2015, the disclosures of eachof which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Disclosure

The present disclosure relates generally to a flow sensor system. Moreparticularly, the present disclosure relates to a flow sensor system forproviding intravenous bolus injections of medication to a patient whichprovides healthcare professionals with an automated record ofmedication, concentration, volume, dose, and time of each injection.Preferably, the system has an ultrasonic flow sensor.

Description of the Related Art

There is a need to reduce medication error at bedside during bolusdelivery. It would be advantageous to provide a record of, andelectronically measure, bolus delivery which allows monitoring bolusdelivery and automatic documentation of bolus delivery as part of apatient's health record. Additionally, it would be advantageous toprovide alerts when bolus delivery inconsistent with a patient's medicalrecord is about to occur.

SUMMARY OF THE INVENTION

The present disclosure provides a system for sensing flow of a fluidicmedicament. The system includes an intelligent injection port which mayattach to an injection site (such as a “Y Site” or a stop cock) formanually administered IV injections. The system includes two mainsub-assemblies: a single-use flow sensor and a reusable base unit, whichfit together prior to use.

In accordance with an embodiment of the present invention, a flow sensorsub-assembly for sensing flow of a fluidic medicament includes a flowtube assembly through which said medicament flows having a flow tubehaving a lumen, an outside diameter, a first end, and a second end. Theflow sensor sub-assembly further includes an inlet fitting having aconical orifice with a shoulder, the shoulder having a matching size andorientation to match an end of the flow tube, wherein the conicalorifice is sized for insertion of either end of the flow tube, such thatan internal passage of the inlet fitting is coaxial and concentric withthe lumen and the end of the flow tube abuts the shoulder. Thesub-assembly further includes an outlet fitting having a conical orificewith a shoulder, the shoulder having a matching size and orientation tomatch an end of the flow tube. The conical orifice is sized forinsertion of either end of the flow tube, such that an internal passageof the inlet fitting is coaxial and concentric with the lumen and theend of the flow tube abuts the shoulder. The flow sensor sub-assemblyfurther includes a first piezo element arranged at an upstream positionof the flow tube assembly and a second piezo element arranged at adownstream position of the flow tube assembly. The first piezo elementis integrated to the inlet fitting and the second piezo element isintegrated to the outlet fitting and each piezo element is spaced aparta pre-selected distance from each other. Each of the conical orificeshas an inner diameter and a taper to engage the outer diameter of saidflow tube thereby allowing capillary insertion of an adhesive duringassembly.

In flow sensor sub-assembly may include an absorber sheath encirclingsaid flow tube, wherein said absorber sheath is comprised of a materialdifferent than said flow tube. The absorber sheath may be heat shrunkonto the outside diameter of the flow tube. Alternatively, the absorbersheath may be adhered to the flow tube. Alternatively, the absorbersheath can be insert molded around the flow tube.

The first piezo element and the second piezo element may be annular inshape and encircle each respective fitting at each respective mountingpoint. The internal passage of either the inlet fitting or the outletfitting is tapered and terminates at an end opposite the shoulder toengage a lumen of a flexible tubing.

In certain configurations, the flow tube assembly is contained within aflow sensor housing having a circuit engaged to the piezo elements,wherein the flow sensor housing is coupled to a flow sensor base whichcontains a microprocessor and the circuit includes connecting pins forproviding the electrical signal from the flow sensor sub-assembly to themicroprocessor within the flow sensor base. The flow sensor sub-assemblymay be disposed of after the flow sensor sub-assembly is used to sensethe flow of at least one fluidic medicament. In certain configurations,the flow sensor base may be used with a different flow sensorsub-assembly.

The internal passage of the inlet fitting may be tapered and terminateat an end opposite the shoulder to engage a Luer type fitting. Theinternal passage of the inlet fitting may be tapered and terminate withan obconic section at an end opposite the shoulder. The conical orificesmay taper and the inlet fitting and the outlet fitting may be two-parttapers having an intermediate shoulder approximately half-way along thelength of the taper.

In accordance with an embodiment of the present invention, a method ofassembly of a flow sensor sub-assembly for sensing flow of a fluidicmedicament includes the steps of providing a flow tube having a lumen,an outside diameter, a first end, and a second end, and providing aninlet fitting having a conical orifice with a shoulder, the shoulderhaving a matching size and orientation to match an end of the flow tube.The method also includes the steps of inserting the flow tube into theinlet fitting conical orifice until an end of the flow tube abuts theshoulder of the inlet fitting, and providing an outlet fitting having aconical orifice with a shoulder, the shoulder having a matching size andorientation to match an end of the flow tube. The method furtherincludes the step of inserting an opposite end of the flow tube into theoutlet fitting conical orifice until the opposite end of the flow tubeabuts the shoulder of the outlet fitting. Additional steps of the methodinclude bonding a first piezo element onto the inlet fitting, bonding asecond piezo element onto the outlet fitting, applying an adhesive to agap between the outer diameter of the flow tube and an inner diameter ofthe conical orifice on the inlet fitting thereby allowing capillarywicking of the adhesive, and applying an adhesive to a gap between theouter diameter of the flow tube and an inner diameter of the conicalorifice on the outlet fitting thereby allowing capillary wicking of theadhesive.

Optionally, the method may also include inserting the flow tube into anabsorber sheath encircling the flow tube, wherein the absorber sheath iscomprised of a material different than the flow tube. Additional stepsof the method may include inserting the flow tube into an absorbersheath encircling the flow tube, and heating the absorber sheath toshrink the absorber sheath onto the outside diameter of the flow tube.The absorber sheath may be adhered to the flow tube. Optionally, themethod may include insert molding the absorber sheath around the flowtube.

The material of the absorber may be one of any polymers or elastomers,such as polyvinylchlorider, silicone rubber, and the like. In oneembodiment, the material of the absorber may be flexible in nature andhave a lower durometer than that of the flow tube. By providing anabsorber having a different and lower durometer than that of the flowtube, the vibrations are maintained within the absorber, rather thanpassed into the flow tube.

In additional configurations, the method may also include the steps ofinserting the inlet fitting into an opening in the first piezo element,and inserting the outlet fitting into an opening in the second piezoelement. The method may also include the step of bonding a flexibletubing to an opposite end of the internal passage of either the inletfitting or the outlet fitting.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of thisdisclosure, and the manner of attaining them, will become more apparentand the disclosure itself will be better understood by reference to thefollowing descriptions of embodiments of the disclosure taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a distally-directed perspective view of a flow sensor systemin accordance with an embodiment of the present invention.

FIG. 2 is a proximally-directed perspective view of a flow sensor systemin accordance with an embodiment of the present invention.

FIG. 3A is a proximal elevation view of a flow sensor system inaccordance with an embodiment of the present invention.

FIG. 3B is a distal elevation view of a flow sensor system in accordancewith an embodiment of the present invention.

FIG. 4A is a side elevation view of a flow sensor system in accordancewith an embodiment of the present invention.

FIG. 4B is an enlarged detail view of a portion of FIG. 4A asillustrated by Detail A.

FIG. 5A is a perspective view of a base of a flow sensor system inaccordance with an embodiment of the present invention.

FIG. 5B is a perspective view of the base of FIG. 5A illustrating theoptical and electrical components.

FIG. 6 is a perspective view of a flow sensor of a flow sensor system inaccordance with an embodiment of the present invention.

FIG. 7 is another perspective view of a flow sensor of a flow sensorsystem in accordance with an embodiment of the present invention.

FIG. 8 is an exploded, perspective view of a flow sensor of a flowsensor system in accordance with an embodiment of the present invention.

FIG. 9 is a perspective view of a flow sensor of a flow sensor system inaccordance with an embodiment of the present invention.

FIG. 10A is a side elevation view of a syringe compatible with a flowsensor system in accordance with an embodiment of the present invention.

FIG. 10B is an enlarged detail view of a portion of FIG. 10A asillustrated by Detail B.

FIG. 10C is a side elevation view of a tip label for a syringecompatible with a flow sensor system in accordance with an embodiment ofthe present invention.

FIG. 11A is a perspective view of a charger for a flow sensor system inaccordance with an embodiment of the present invention.

FIG. 11B is an enlarged detail view of a portion of FIG. 11A rotated ata clockwise angle as illustrated by Detail C.

FIG. 11C is a top elevation view of a charger for a flow sensor systemin accordance with an embodiment of the present invention.

FIG. 11D is a cross-sectional view taken along line X-X of FIG. 11C,with a base of a flow sensor system received within a portion of thecharger, in accordance with an embodiment of the present invention.

FIG. 12 is a perspective view of a flow sensor and a mount in accordancewith an embodiment of the present invention.

FIG. 13 is a perspective view of a flow tube sub-assembly in accordancewith an embodiment of the present invention.

FIG. 14A is a schematic representation of a computer display in ananesthesia view in accordance with an embodiment of the presentinvention.

FIG. 14B is a schematic representation of a computer display in atabular view in accordance with an embodiment of the present invention.

FIG. 15 is a schematic side view of a process of applying an adhesive tothe transducer, end fittings, and absorber sheath in accordance with anembodiment of the present invention.

FIG. 16 is a perspective cross-sectional view of an inlet fitting inaccordance with an embodiment of the present invention.

FIG. 17 is a perspective cross-sectional view of an outlet fitting inaccordance with an embodiment of the present invention.

FIG. 18 is a cross-sectional side view of an injection port engaged withan inlet fitting engaged with transducer and an absorber in accordancewith an embodiment of the present invention.

FIG. 19 is a cross-sectional side view of an outlet fitting engaged witha transducer and an absorber in accordance with an embodiment of thepresent invention.

FIGS. 20A-D show a process for applying an absorber sheath and endfittings to a flow tube in accordance with an embodiment of the presentinvention.

FIGS. 21A-D show a process for applying an absorber sheath and endfittings to a flow tube in accordance with an embodiment of the presentinvention.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate exemplary embodiments of the disclosure, and suchexemplifications are not to be construed as limiting the scope of thedisclosure in any manner.

DETAILED DESCRIPTION

The following description is provided to enable those skilled in the artto make and use the described embodiments contemplated for carrying outthe invention. Various modifications, equivalents, variations, andalternatives, however, will remain readily apparent to those skilled inthe art. Any and all such modifications, variations, equivalents, andalternatives are intended to fall within the spirit and scope of thepresent invention.

For purposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”,“longitudinal”, and derivatives thereof shall relate to the invention asit is oriented in the drawing figures. However, it is to be understoodthat the invention may assume various alternative variations, exceptwhere expressly specified to the contrary. It is also to be understoodthat the specific devices illustrated in the attached drawings, anddescribed in the following specification, are simply exemplaryembodiments of the invention. Hence, specific dimensions and otherphysical characteristics related to the embodiments disclosed herein arenot to be considered as limiting.

As used herein, proximal shall refer to a part or direction located awayor furthest from a patient (upstream), while distal shall refer to apart or direction towards or located nearest to a patient (downstream).Also, a drug substance is used herein in an illustrative, non-limitingmanner to refer to any substance injectable into the body of a patientfor any purpose. Reference to a patient may be to any being, human oranimal. Reference to a clinician may be to any person or thing givingtreatment, e.g., a nurse, doctor, machine intelligence, caregiver, oreven self-treatment.

FIGS. 1-12 illustrate an exemplary embodiment of a flow sensor system200 of the present disclosure. Referring to FIGS. 1-12, a flow sensorsystem 200 of the present disclosure includes two main assemblies whichfit together prior to use: a flow sensor 210 and a base 220. In oneembodiment, the flow sensor 210 can be a single-use flow sensor which isengageable with reusable base 220. The flow sensor system 200 is anintelligent injection port. The flow sensor system 200 is attachable toan injection site (“Y Site” or stop cock, for example) for manuallyadministered IV injections.

The flow sensor system 200 of the present disclosure can reducemedication error at bedside during bolus delivery. The flow sensorsystem 200 of the present disclosure can also provide a record of andelectronically measure bolus delivery, which allows monitoring bolusdelivery and automatic documentation of bolus delivery as part of apatient's health record. The flow sensor system 200 of the presentdisclosure can also provide alerts when bolus delivery inconsistent witha patient's medical record is about to occur.

Referring to FIGS. 1-5B, in one embodiment, the base 220 is anon-sterile, reusable device that houses a battery, a scanner (eitheroptical, mechanical, inductive, capacitive, proximity, or RFID),electronics, and wireless transmitter. In some embodiments, the base 220is battery powered, and rechargeable. In some embodiments, each base 220has a unique serial number imprinted on a surface of the base 220 orembedded therein that may be transmitted to a data system before use.The data system can be a local computer or tablet “Computer”, a cellularphone, another medical device, or a Hospital Data System.

In one embodiment, the base 220 is removably connectable to the flowsensor 210. Referring to FIGS. 5A and 6-9, the base member 220 and themechanical connection of the flow sensor 210 to the base member 220 isdescribed. The base member 220 includes at least one deflectable wingtab 280 defining an opening for receiving at least a portion of the flowsensor 210 therein and for securing the flow sensor 210 within a portionof the base 220 prior to use. In one embodiment, a pair of wing tabs 280secure the flow sensor 210 within the base 220. Optional gripping ribs395 may be provided on an exterior profile for enabling a user to graspthe base portion 220.

An interior profile of the wing tab 280 may be provided with a catch 389for corresponding engagement with a tab 189 provided on the flow sensor210, as shown in FIG. 6, to restrain the flow sensor 210 within the base220, as will be discussed further herein. The wing tabs 280 may beflexible to the extent that they may be outwardly deflected to allow forpassage of the flow sensor 210 thereover. The interior of the wing tab280 may be provided with a pin cam 388 which allows a pin 188 of theflow sensor 210, as shown in FIG. 7, to ride along such that the flowsensor 210 is moved proximally during assembly onto the base 220, toprecisely align various optical and electrical components of the flowsensor 210 and the base member 220, as will be discussed further herein.

Referring to FIGS. 5B and 6-9, the base member 220 and the electricalconnection of flow sensor 210 to the base member 220 is described. Thebase 220 includes an activation/engagement button 350 which allows foran indication that the flow sensor 210 has been engaged with the base220. In one embodiment, the activation/engagement button 350 signals toa microprocessor within the base 220 that a syringe has been properlyengaged with the sensor 210 and its injection port 130.

The base 220 further includes a plurality of contacts 386 (FIG. 5B) forelectrically engaging corresponding electrically active portions of theplurality of contact pins 385 (FIG. 7). A contour protrusion 488surrounds at least a portion of the tongue 286. As shown in FIG. 7, abottom surface of the sensor 200 includes a pin seal 384 surrounding aplurality of contact pins 385 to prevent contamination, thus minimizingelectrical disruptions. In some embodiments the plurality of pins 385comprise a four pin connector with two pins electrically connected toeach piezo element 150, 151, as will be discussed further. In otherembodiments, the plurality of pins 385 comprise a six pin connector withtwo pins electrically connected to each piezo element 150, 151 and twopins electrically connected to a battery (not shown) in the flow sensor210.

The base member 220 further includes a tongue 286 surrounded by ashoulder 486 having a plurality of contacts 386 for electricallyengaging corresponding electrically active portions of sensor 200 and acharger 900 (FIG. 11A), as will be discussed herein.

Referring to FIGS. 1-4B, 6-9, and 13, in one embodiment, the flow sensor210 is a pre-sterilized disposable having an injection port 130 and adistal tubing connection, such as a Luer tip 109.

The flow sensor 210 may include a flow tube sub-assembly 10 consistingof a flow tube 100 having an outlet end 101 and an inlet end 102. Theoutlet end 101 may be provided in fluid communication with an outlettubing 110 having an outlet connection 105 including a Luer tip 109which may be optionally covered by a Luer cap 108. In a preferredembodiment, the outlet connection 105 is a plastic connector with a Luertip 109, however, any suitable method to inject the medicament into apatient is envisaged to be within an aspect of an embodiment of theinvention. For example, it may be desirable to replace the outletconnection 105 and tubing 110 with a needle for directinjection/infusion into a patient. Furthermore, it may be desirable tointegrate the base 220 into a medication pen or infusion device for thedelivery of insulin.

The inlet end 102 may be coupled to the reservoir of a medication pen orinfusion reservoir. The inlet end 102 of the flow tube 100 may beprovided in fluid communication with an injection port 130, and mayoptionally include a connection such as a threaded Luer lock 131 whichis engageable with a source of a fluid to be injected. A pierceableseptum 139 may be provided with the injection port 130 for maintainingsterility prior to use.

In a preferred embodiment, the injection port 130 is a plastic containerwith a split septum 139, however, any suitable method to inject themedicament through a flow sensor inlet 180 to a patient is envisaged tobe within an embodiment of the present invention. For example, it may bedesirable to replace the injection port 130 for direct connection to amedicament delivery device. In addition, it may be desirable tointegrate the flow sensor inlet 180 to accept a direct fluidicconnection to a medication delivery device.

In one embodiment, the flow tube 100 is comprised of a medical gradestainless steel and is approximately 50 mm long with a 1.0 mm innerdiameter and a 1.6 mm outer diameter.

The flow sensor 210 also includes a first piezo element or upstreamtransducer 150 and a second piezo element or downstream transducer 151.The first piezo element 150 may be provided with an inlet fitting 180,as shown in FIG. 8, for coupling with the injection port 130. Similarly,the second piezo element 151 may be provided with an outlet fitting 190,for coupling with the outlet tubing 110.

The flow sensor 210 can be supplied in a sterile package for a singlepatient use. In one embodiment, labeling is printed on the individualsterile package. In one embodiment, each flow sensor 210 has a uniqueserial number imprinted on a portion of its surface. In someembodiments, there are electronics in the flow sensor 210 which retain aunique identifier. These identifiers are transmitted eitherautomatically or manually to a data system during use and datacollection. In one embodiment, at the inlet end 102 of a flow sensor 210the injection port 130 is a common needleless, Luer-Lok type. Typically,the inlet port or the injection port 130 is cleaned prior to giving aninjection according to hospital policy. Additionally, flushing the flowsensor 210 with an IV fluid (e.g., normal saline syringe) is desirablebefore use. The injection port 130 on the flow sensor 210 typicallysupports up to 100 injections. In one embodiment, the flow sensor 210has a male Luer-Lok connection, e.g., an outlet connection 105 having aluer tip 109, on a one-inch IV tubing pigtail at the outlet end 101.This male Luer-Lok connection may be attached to an IV line at a Y-siteor IV manifold. Each flow sensor 210 has a unique serial number, howeverit may be desirable to only display a portion of the serial number on aportion of the exterior of the flow sensor 210. For example, the last 4digits of the serial number may be imprinted on the surface next to itsbar code. This human readable number is used to visually identify a flowsensor 210 within wireless range of communication of a computer. In someembodiments, the flow sensor 210 measures with an accuracy of ±5% forbolus volumes>1.0 mL to 55 mL and ±20% for bolus volumes of 0.4 to 1.0mL and has a dead-space volume of less than 0.3 mL.

Referring to FIGS. 11A-11D, in one embodiment, an optional separatecharger 900 is compatible with the flow sensor system 200 and rechargesa battery in the reusable base 220, if required, for reuse of the base220. Referring to FIGS. 11A-11D, in one embodiment, the charger 900includes a charger base 905 having an opening 925 for receiving the base220, the opening 925 having charging pins 950 which engage correspondingcontacts 386 in the reusable base 220. The charger 900 may include asloped floor 930 for allowing disinfection liquid to drain therefrom.The device may also include elevated feet 999 to assist in drainage.

Reusable bases are typically supplied non-sterile and requiredisinfection and charging before use. It is preferred to disinfect eachbase 220 before first use. Typical commercial hospital disinfectantsinclude alcohol-based quaternary ammonium, e.g., Metrex Research CaviWipes. In some embodiments, the base 220 can be used up to 500 times.Preferably, a rechargeable lithium ion battery is used within the base220 and is not removable from the base 220. It is envisaged that afully-charged base 220 will accommodate an entire patient case. In someembodiments, each base 220 is identified by labeling on the bottom ofthe device. Optionally, bases 220 are provided in individual boxes andeach box is in a case package. The charger 900 may also include a powerindicator 995. In one embodiment, when the base 220 is connected to acharger 900, up to four green light bars will illuminate on the top. Thenumber of solid green light bars indicates the level of charge. A greenblinking light on the base 220 will indicate it is recharging. In someembodiments, a useful life indicator is employed when the base 220 isconnected to a charger 900 by use of a red light that indicates that thebase 220 has exceeded its useful life. Optionally, on the Computer, anerror message will display when a flow sensor system 200 whose usefullife is completed is wirelessly connected to a tablet during patientsetup. It would then be desirable to replace the base 220 with anotherand repeat the wireless connection to the Computer. Optionally, the flowsensor system 200 is provided in a mount which is an appliance that fitsa standard Clarke socket to keep the flow sensor system 200 in place atthe patient's bedside. Additionally, it may be desirable to clean anddisinfect the charger 900 by using the procedure used for cleaning anddisinfecting the base 220.

In one embodiment, the flow sensor system 200 supports injections usingany Luer-lock type syringe. For example, referring to FIGS. 10A-10C, theflow sensor system 200 is compatible with a syringe 800 that is labeled.In one embodiment, the syringe 800 includes scale markings 805, a distaltip 810, a luer tip 815, a proximal end 820, a flange 825, a tip label850 having human readable indicia 852 and machine readable indicia 854,a barrel label 860 having human readable indicia 862, and a plunger 890.

The base 220 of the flow sensor system 200 includes optics and a digitalcamera disposed within or behind a first window 360, as shown in FIG. 2,capable of reading the machine readable indicia 854 provided on a label850 of an encoded syringe. The first window 360 may be precisely alignedwith Luer lock threads 131 present on the flow sensor 210 when the flowsensor 210 is assembled with the base 220, thus aligning the machinereadable indicia 854 present on the label 850 on the syringe 800 duringan injection cycle and/or medication determination cycle. The base 220may further include a second window 370, as shown in FIG. 5, having alight source for providing adequate lighting to the camera disposedwithin or behind window 360.

Additionally, the flow sensor system 200 is designed to work withencoded syringes that have a special barcode identifier on the Luercollar of the syringe, called “encoding”. Preferably, encoded syringesinclude commercially-available drugs in prefilled syringes with aspecial barcode that stores information about the medication containedwithin the syringe. Encoded syringes are ready-to-use, passive, anddisposable. The flow sensor system 200 also accommodates syringes nothaving encoding. The encoding syringes store the drug name andconcentration contained within the syringe. Additional characteristicssuch as drug source, container size, drug manufacturer source, drugcategory color, among others, may also be included. When an encodedsyringe is attached to the injection port 130 of the flow sensor 210,this barcode information is read by a scanner in the base 220 wirelesslytransmitted by the flow sensor system 200 to the data system.Preferably, the 2-D barcodes will be added to syringes during thefilling process.

In one embodiment, the flow sensor system 200 contains a device tocapture and transmit an image of a 2-D barcode on the Luer collar of thesyringe, and wirelessly transmit this image to a “Computer”. Typicallythe Computer is a tablet computer communicating with multiple flowsensor systems 200. The 2-D barcode contains data, typically includingthe name and concentration of the drug in the syringe among other data.The Computer decodes this image, and displays and announces the drugattached. The barcode can contain the drug name and concentration. Asthe drug is injected, the flow sensor 210 in conjunction with the base220 ultrasonically measures the volume of the injected drug and the timethe drug was administered. This information may be stored in the flowsensor system 200 for later transmission to the Computer. The Computeruses this information to provide clinicians with an automated record ofthe drug name, concentration, volume, dose, and time of injection. Themedication administration information is time stamped and displayed forclinical reference. Not all syringes used by the healthcare professionalwill contain a 2-D barcode. If a syringe without a 2-D barcode isinserted into the flow sensor system, the injection port 130, the flowsensor system 200 will prompt the user to manually enter the drug nameand concentration into the computer. Information that is manuallyentered into the flow sensor system 200 is included in the patientmedication record.

In one embodiment, the Computer can use a radio to wirelesslycommunicate with the flow sensor system 200 using an RF signal at 2.4GHz to form a local medical device network. A number of flow sensorsystems 200 and Computers may be used in the same vicinity such as apre-operative care area or a post anesthesia care unit (PACU). Alertmessages are communicated between the flow sensor system 200 and theComputer to advise the clinician of various operational characteristicsof the flow sensor system 200. Some of these alerts inform the clinicianof potential hazardous situations to allow user action to prevent harmto the patient or loss of medical data. Preferably, a lost wirelesscommunication message will display when communication is lost betweenthe flow sensor system 200 and the Computer. Preferably, all medicationadministration data from the flow sensor system 200 is transferred tothe specific patient's medical record. In the event of a communicationloss, medication administration data will be stored locally at the flowsensor system 200 and transferred to the Computer when communicationsare resumed.

The Computer may operate in a variety of modes. Typically the Computerhas specialized flow sensor system 200 software for operations, a touchscreen, and a wireless communications (Radio). It is typically mountednear an anesthetist or nursing work envelope and it may be removed forhand-held use. When the Computer is used in a hospital having a paperanesthesia record, the Computer supports features that assist withdocumenting the flow sheet portion and may help clinicians make theright decisions. In this configuration, the Computer complements thepaper recordkeeping activities by tracking and displaying injectionsgiven through the flow sensor system 200. The Computer also enablesclinicians to manually document other pertinent IV drug injection andinfusion information.

In one embodiment, the software screens follow a three-step approachconsisting of: (1) connecting the flow sensor system 200 to theComputer; (2) setting up a patient's flow sensor system 200 for use; and(3) viewing medication administration in multiple views.

In some embodiments, a view on the computer displays anesthesia basedinformation in an anesthesia view, as shown in FIG. 14A. Preferably,this view provides information about the patient and displays drugname/concentration and dose for a current injection as well as ahistorical list of medications that have been delivered to the patientsince the current case was opened. It may also include a listing ofinfusions given to the patient, if the clinician recorded them on theComputer. In this view, up to three injection bars display across thetop of the screen, one corresponding to each wirelessly connected flowsensor system 200. Each injection bar is a real time representation ofthe medication being administered through an individual flow sensorsystem 200. When an encoded syringe is attached to a single flow sensorsystem 200, the injection bar displays the drug name and concentration.When a non-encoded syringe is attached, the injection bar will promptthe clinician to identify the medication and concentration beingdelivered. As the medication is being delivered, the volume pushed (inmL) and the corresponding dose displays in real time in the injectionbar on the Computer display.

A flow sensor system 200 of the present disclosure may also provideoptional medication history. For example, an anesthesia view can includea historical list of medications delivered to the patient organized bythe surgical care area (medications given in the transition time betweencare areas, will post to the next care area) arranged in a flow sheetformat. Preferably, this view includes all medications that wereadministered to the patient since the flow sensor system 200 wasactivated with the more recent medication administrations preferably atthe bottom of the list. A scroll bar is enabled when the list exceedsthe visible space on the screen of the Computer. Preferably, when a newmedication is added, the medication list scrolls automatically so thenew medication name is visible. In the view, preferably a color tilecorresponding to American Society for Testing and MaterialsInternational (ASTM) standards and endorsed by the American Society ofAnesthesiologists displays to the left of the drug name. Optionally, aclinician may also specify that an admixture (mixed medication), or adiluted or reconstituted medication was delivered. Optionally, theComputer displays a case header which lists the patient name, date ofbirth, age in years, medical record number, and patient identificationnumber. Optionally, the Computer will indicate that the patient has “noknown allergies”. Preferably, if the patient has allergies that text isreplaced by a button, more preferably, the button has a number on thebutton that indicates the number of allergies.

A flow sensor system 200 of the present disclosure may also provide anoptional tabular view, as shown in FIG. 14B. For example, the tabularview is an alternate view for the clinician to interact with the flowsensor system 200. Similar to the anesthesia view described above, thisview provides information about the patient and displays drugname/concentration and dose for a current injection as well as ahistorical list of medications that have been delivered to the patient.It may also include a listing of infusions given to the patient, ifrecorded by the clinician. The tabular view has many of the features ofthe anesthesia view; however, it is arranged in a tabular format.Preferably, the column headings in this view include time administered,medication with concentration, dose, and unit total. Optimally, themedications are displayed in reverse chronological order with mostrecent medication administered at the top of the list.

In one embodiment, the Computer provides two types of messages: (1)“Clinical” and (2) “System”. Clinical messages are alerts and remindersthat relate directly to an aspect of patient care delivery (e.g.contraindication or a reminder that it may be time to re-doseantibiotics). System messages provide status on relevant systemoperating parameters.

Messages provide instructions and a button for acknowledging orresolving. Messages display on the Computer until they are acknowledgedor are no longer clinically relevant. Messages can be answered any timeduring a case. Prior to pausing or closing a case, the clinician isprompted to respond/answer unresolved medication messages generatedduring the case. An allergy alert illuminates the flow sensor system 200and displays on the Computer when a clinician attaches an encodedsyringe or selects a medication for a non-encoded syringe to which thepatient has a known allergy. Optionally, this message may be overridden.

When dosing antibiotics, preferably the Computer tracks elapsed timesince an antibiotic was last administered and displays and announces anantibiotic redosing message if the configured redosing interval haselapsed. The redosing interval is individual to each antibiotic, and itis configured in the drug library of the Computer or Gateway, as furtherdescribed below. In one embodiment, the flow sensor system 200 does notprevent or block the injection of a medication. In other embodiments,the flow sensor system 200 is able to block the injection of amedication.

In one embodiment, the Computer posts a message when the volume injectedthrough the flow sensor system 200 was not measured. This may occur whenthe volume measured is outside of a range of sensing of the flow sensorsystem 200.

Optionally, the Computer wirelessly communicates bi-directionally with asoftware application that acts as a central hub to which all Computers(and thus multiple upon multiples of flow sensor systems 200) areconnected, the “Gateway”. Preferably, the Gateway is also connected tothe hospital's other networked information systems. The Gateway allowsall Computers to share patient case information such as drug name, dose,and time delivered with each other, and with the hospital's networkedinformation systems. The Gateway also allows Computers to receivepatient information such as patient drug allergies and patient drugorders from other networked hospital information systems.

Utilizing the flow sensor system 200 of the present disclosureencompasses the steps of connecting the flow sensor 210 to the patient'scatheter or injection port (Y-site). Preferably, the flow sensor 210 andline is flushed. The flow sensor 210 is keyed to an individual patientusing a unique serial number and the base 220 records medicationadministration through the port at the inlet end 102 of the flow sensor210.

When a syringe 800 is attached to the injection port 130, the flowsensor system 200 identifies the medication and concentration for anencoded syringe by optically imaging and decoding a barcode on theLuer-Lok collar of the syringe 800. This information is wirelesslytransmitted to the Computer. Preferably, the Computer displays andaudibly announces the drug attached. The Computer also may performallergy safety checks based on the patient's medical record.

In one embodiment, as the drug is injected, the flow sensor system 200measures the volume dosed ultrasonically. The flow sensor system 200wirelessly sends volume measurement information to the Computer. TheComputer uses this information to provide clinicians with a medicationadministration record which is time stamped and displays for clinicalreference during surgical procedures. Manually entered infusions andother information pertaining to non-encoded drug injections may beincluded in the patient medication record in the Computer and theGateway. The Computer wirelessly communicates with the Gateway on thehospital network, and it may send medication administration to HospitalInformation Systems, when configured, for reporting and electronicrecordkeeping purposes. Preferably, the Computer wirelessly communicateswith the existing Hospital Network using a standards based IEEE802.11a/b/g/n enterprise WLAN network. The Gateway software andaccompanied database will be a part of the hospital's enterpriseinformation system. A number of Computers may be connected to thehealthcare enterprise wireless network and to the intended Gatewaysoftware and database. Preferably, the Gateway and accompanied databaseprovides a list of patients for the user to select and a formularylibrary of medications and fluids for injection or infusion. In oneembodiment, actual medication and fluid administration data are sent tothe Gateway and accompanied database for recordkeeping. Once recorded onthe Gateway and accompanied database these data are preferably availablein other care areas when the patient is transferred and the flow sensorsystem 200 is wirelessly connected to a Computer. Preferably, in theevent of a communication loss, medication administration data will notbe sent to the Gateway and therefore not available in the next carearea.

Referring to FIGS. 1-12, use of a flow sensor system 200 of the presentdisclosure will now be described. First, preparing the flow sensorsystem 200 for an injection will be discussed.

In one embodiment, the flow sensor system 200 is prepared, attached toan IV line, and assembled for use. Preferably, there are pre-printedinstructions located on the flow sensor 210 sterility pouch. First, auser obtains a flow sensor 210 in its sterile packaging and afully-charged and disinfected reusable base 220. In one embodiment, afully-charged base 220 has sufficient power for at least 24 hours of useunder typical conditions. Optionally, the base 220 provides a visualindication of charge level via a display.

Next, the flow sensor 210 is flushed with sterile IV fluid beforeattaching to the Y-site. In one embodiment, the flow sensor 210 isflushed with more than 8 mL of sterile IV fluid. After flushing, a usercan visually inspect the IV line for leaks, air, or blockage.

Next, a user attaches the flow sensor 210 to the base 220 by joining theflow sensor 210 (tubing side) and base 220 front sections first, andthen snapping the two together. Preferably, an audible snapping sound isheard to indicate a secure connection between the flow sensor 210 andthe base 220. In one embodiment, connecting the flow sensor 210 to thebase 220 automatically powers on the flow sensor system 200. In oneembodiment, the connection of the flow sensor 210 to the base 220 isverified by a blinking light on the base 220. In other embodiments,other indicators may be used. Catch 389 of the base 220, shown in FIG.5, engages tab 189 of the flow sensor 210, shown in FIG. 6, to restrainthe flow sensor 210 with the base 220 prior to initiation of aninjection. In one embodiment, deflection of the wing tab or wing tabs280 moves tab 189 with respect to catch 389 to initiate engagement ordisengagement therewith. When the flow sensor 210 is assembled to thebase 220, a cantilever 650 provided on the base 220, such as a lowerhousing 212 as will be discussed herein, is aligned with button 350provided on the base 220. The interior of the wing tab 280 may also beprovided with a pin cam 388 which allows pin 188 of the flow sensor 210,as shown in FIG. 6, to ride along such that the flow sensor 210 is movedproximally during assembly onto the base 220. During engagement, tongue286 shown in FIG. 5, is engaged within an opening 285 shown in FIG. 7.With continued reference to FIGS. 5 and 7, a vault 485 having ribs 487on the flow sensor 210 as shown in FIG. 7, has a corresponding exteriorprofile taken with the shoulder 486 of the base 220, as shown in FIG. 5,to engage for alignment of the first window 360 to precisely align withLuer lock threads 131 when the flow sensor 210 is assembled to the base220.

In some embodiments, where appropriate, the flow sensor system 200 issecured to a surface in preparation for giving injections. For example,in some embodiments, referring to FIG. 12, a mount 1100 is used tosecure the flow sensor system 200 to a surface. During this step, it isimportant to avoid kinks in the line between the flow sensor system 200and IV line.

The flow sensor system 200 is now ready for delivery of IV medications.Preferably, any medications given through the flow sensor system 200will be recorded in the electronic base 220 memory. In one embodiment,in the event of a flow sensor system 200 failure (excluding the IV fluidpathway), the flow sensor system 200 will still allow standardmedication or fluid delivery through the port.

Next, giving an injection using the flow sensor system 200 will bediscussed. First, the injection port 130 is cleaned by swabbing the hubaccording to normal hospital procedure. Next, a syringe 800 can beattached to the injection port 130 of the flow sensor 210 by completelyturning the syringe 800 until the syringe 800 stops, i.e., a secureconnection between the syringe 800 and the injection port 130 is made.Ideally, the caregiver double checks each medication name andconcentration on the syringe 800 prior to attachment to the injectionport 130 to assure the correct medication is given. During the injectioncycle and/or medicament determination cycle, when syringe tip 810contacts a syringe protrusion 652, as shown in FIG. 4B, the cantilever650 is deflected radially from the longitudinal axis of the syringe 800.A pad protrusion 651 depresses button 350 on the base 220 and the button350 signals the microprocessor to act.

Next, the drug and concentration displayed and announced by the Computeris verified as the intended drug and concentration. In one embodiment,the base 220 will alert the caregiver that an allergy is detected by analert, for example, by flashing red, green, and yellow lights if amedication allergy is detected. Optionally, the Computer calculates apotential allergy reaction and provides an alert when any of theseconditions is true: (1) an encoded syringe is inserted into the flowsensor 210 and the drug matches the patient's allergy profile; or (2) anon-encoded syringe is inserted into a flow sensor 210 and you select adrug from the select medication screen that matches the patient'sallergy profile. If one of these conditions is true, the allergy alertflag on the Computer configuration is turned on.

In one embodiment, there is no check valve in the flow sensor 210, noris one needed to use the flow sensor 210 safely and effectively.Typically, the flow sensor system 200 measures 0.4 mL to 55 mL perinjection. If the injection flow rate is slow or a small volume isdelivered (<0.4 mL) preferably an alert will display on the Computer.Optionally, an alarm is configured to detect rapid delivery from a largevolume, e.g., 50 mL syringe. In this case, an alert is provided to checkthe dose.

In one embodiment an indicator 375, such as a series of four LEDindicators, turn on in sequence to indicate to the user that fluid ismoving through the flow sensor 210. When base 220 is mounted in thecharger 900, the indicator 375 can indicate a level of battery charge ofthe base 220.

In one embodiment, it is preferred to follow all medication injectionsthrough the flow sensor system 200 with an encoded normal saline flushsyringe to ensure the full dose of medications reaches the patient,especially when successively delivering two incompatible medications.Optionally, the flow sensor system 200 records such saline flushactivity.

In one embodiment, injections are recorded whether or not the flowsensor system 200 is wirelessly connected to the Computer. The base 220stores injection information in its memory and transmits thisinformation upon wireless connection to the Computer.

In one embodiment, the Computer can accommodate multiple flow sensorsystems 200 connected to one patient at a time. An additional flowsensor system 200 may be added at any time during a patient's treatment.When a flow sensor system 200 is connected to a Computer and there is nosyringe attached to the flow sensor 210, the active injection bar reads“Sensor Connected, No syringe”. On the Computer display, a batterystatus icon in the upper right corner of the injection bar indicates thebattery charge level of the base 220 to which the flow sensor 210 isconnected. For each injection a caregiver may enter a comment on theComputer.

The present disclosure provides a flow sensor sub-assembly for sensingflow of a fluidic medicament. The flow sensor sub-assembly includes afirst spring contact and a second spring contact. In one embodiment, thespring contacts are secured to a base that has a circuit for conductingan electrical signal to and from the spring contacts to amicroprocessor. The first spring contact is in electrical communicationwith a first piezo element and the second spring contact is inelectrical communication with a second piezo element. The first springcontact has a first contact force against the first piezo element andthe second spring contact has a second contact force against the secondpiezo element, and the first contact force is equivalent to the secondcontact force. The present disclosure also provides a circuit board forinterfacing to a flow sensor having a plurality of piezo elements fortransmitting a flow signal indicative of flow of a fluidic medicament.

A spring contact of the present disclosure provides electrical contactto a piezo element. For example, a spring contact of the presentdisclosure provides electrical contact to a silvered surface of apiezoelectric crystal. Furthermore this contact provides a spring forceselected to accommodate assembly tolerances, temperature variation,electrical requirements, material selection for a long life to silver,and assembly features for a single-sided printed circuit board assembly(PCBA) attachment. The flow sensor sub-assembly of the presentdisclosure provides for four contacts used in a sensor to have the sameforce on both surfaces of each of two piezo elements, such as crystals,in a single transducer.

A circuit board of the present disclosure provides a single-sided PCBA.The single-sided PCBA of the present disclosure provides a lower costdesign than conventional double-sided PCBA designs. The circuit board ofthe present disclosure also provides a means to maintain mechanicalloading of the crystal contacts when the transducer is inserted to thePCBA.

Electrical contacts to the ultrasound crystal have previously beenaccomplished by soldering wires to a silver coating. A spring contact ofthe present disclosure provides a cost reduction method by using thespring contacts to connect to the crystal. In particular, a single-sidedprinted circuit board (PCB) of the present disclosure provides for alower cost design and a through hole contact design. The design of thepresent disclosure includes the force exertion by the spring constant,dimension of separation between contacts, material type of the springs,the range of forces necessary, and tolerance control of forces exertedby the spring contact, which are all important to eliminate soldering.If soldering is too hot it often takes silver off the surface of thecrystal. Another problem with soldering is leaving too much solderbehind, which may also cause loading of the ultrasonic physicalcharacteristics. Consistent electrical and physical contact(repeatability) for both crystals is important as well as sensor tosensor calibration. The forces cannot be too high (potential for aslurry to develop) or too low (variable impedance).

The flow sensor sub-assembly of the present disclosure provides a highvolume, disposable design with benefits for its cost, reliability, andrepeatability. The flow sensor sub-assembly of the present disclosureallows for future automation features. The flow sensor sub-assembly ofthe present disclosure provides for maximal tolerance designed inconditions. The flow sensor sub-assembly of the present disclosure isable to fit inside the housing of a flow sensor 210.

Referring to FIGS. 8 and 13, a flow tube sub-assembly 10 for a flowsensor 210 for sensing flow of a fluidic medicament generally includes aflow tube 100 having a flow tube inlet 102 and a flow tube outlet 101,through which a medicament flows, a first piezo element 150 arranged atan upstream position of the flow tube 100 and a second piezo element 151arranged at a downstream position of the flow tube 100, a first springcontact 750, and a second spring contact 750. The flow tube inlet 102may be coupled to the reservoir of a medication pen or infusionreservoir. As described herein, in some embodiments, the inlet end 102of the flow tube 100 may be provided in fluid communication with theinjection port 130.

In one configuration, the sub-assembly 10 for a flow sensor 210 may beutilized as a flow sensor 210 and inserted into the base 220, wherecontacts 750 are integrated into the base 220 rather than as a componentof the housing 211, 212 of the flow sensor 210. Preferably, the upstreamtransducer 150 and downstream transducer 151 are interchangeable,however, it is envisaged that they may be purposefully constructed fortheir respective positions on the flow sensor sub-assembly 10.

In one embodiment, the first piezo element 150 and the second piezoelement 151 are mounted apart a pre-selected distance from each other.In one embodiment, each of the spring contacts 750 are secured to abase, e.g., a circuit board 700. The circuit board 700 includes acircuit for conducting an electrical signal to and from the springcontacts 750 to a microprocessor. The first spring contact 750 is inelectrical communication with the first piezo element 150 and the secondspring contact 750 is in electrical communication with the second piezoelement 151. The first spring contact 750 has a first contact forceagainst the first piezo element 150 and the second spring contact 750has a second contact force against the second piezo element 151. In oneembodiment, the first contact force is equivalent to the second contactforce. In another embodiment, circuit board 700 can contain anon-volatile memory containing the serial number of the sensor 210,calibration data and/or flow calculation constants for communication tothe electronic microprocessor of the base 220.

Referring to FIGS. 13 and 15, in one embodiment, the flow sensor 210includes an inner flow tube 100 and end fittings, e.g., an inlet fitting180 at an inlet end 102 and an outlet fitting 190 at an outlet end 101,for securing the inner flow tube to the respective end fittings 180,190. In one configuration, a transducer 155 is coupled to at least oneof the inlet fitting 180 and the outlet fitting 190. In a furtherconfiguration, a transducer 155 is coupled to each of the inlet fitting180 and the outlet fitting 190. In still a further configuration, afirst piezo element 150 is coupled to the inlet fitting 180 and a secondpiezo element 151 is coupled to the outlet fitting 190.

A transducer adhesive 156 may be used to bond a transducer 155, such asfirst piezo element 150 and second piezo element 151 to a fitting 185,such as the inlet fitting 180 and the outlet fitting 190. Transduceradhesive 156 bonds the transducer 155 to the fitting such that energyfrom the transducer 155 is transmitted optimally across theTransducer-Fitting Transmission Zone 159, as shown by arrow T, whileminimizing the losses at the Fitting-Tube Transmission Zone 158, asshown by arrow T1. Preferably, the fitting adhesive 186 dampens out ofphase and/or rogue vibrations induced in the end fittings 180, 190 bythe transmission of sound energy between the first and second piezoelements 150, 151 and the end fittings 180, 190.

The first piezo element 150 is arranged at an upstream position of theflow tube 100 and the second piezo element 151 is arranged at adownstream position of the flow tube 100. The first and second piezoelements 150 and 151 are configured to transmit a flow signal indicativeof a flow of the fluidic medicament in the flow tube 100. In anembodiment, the first piezo element 150 and the second piezo element 151are annular in shape and encircle the flow tube 100 at each respectivemounting point. In an embodiment, the first piezo element 150 and thesecond piezo element 151 are mounted apart a pre-selected distance fromeach other. Each of the first and second piezo elements 150, 151 aremounted to the end fittings 180, 190, respectively. Each of the firstand second piezo elements 150, 151 are bonded to the end fittings 180,190 by transducer adhesive 156 such that energy from the transducers150, 151 is transmitted optimally across the Transducer-FittingTransmission Zone 159 of each end fitting 180, 190. The adhesive canincrease or maximize the energy transfer across the Transducer-FittingTransmission Zone 159, while reducing or minimizing the losses.Preferably, the transducer adhesive 156 facilitates the transmission ofsound energy between the first and second piezo elements 150, 151 andthe end fittings 180, 190. The transducer adhesive 156 can be amoderately viscous, medical grade adhesive. Air gaps between the firstand second piezo elements 150, 151 and the end fittings 180, 190 can beeliminated to enable more efficient sound energy transmission.Preferably, the transducer adhesive 156 maintains its properties aftersterilization.

Referring again to FIGS. 13 and 15, an absorber sheath 500 may encirclesthe flow tube 100. In some embodiments, there may be a gap between theabsorber sheath 500 and the inlet fitting 180 exposing a portion of theflow tube 100 at the inlet end 102 and/or a gap between the absorbersheath 500 and the outlet fitting 190 exposing a portion of the flowtube 100 at the outlet end 101. For example, the absorber sheath 500 maybe positioned about 6 mm away from the inlet fitting 180 and about 6 mmaway from the outlet fitting 190. The absorber sheath may comprise amaterial with an acoustical transmission rate different than anacoustical transmission rate of a material of the flow tube 100. Forexample, the flow tube 100 can comprise a stainless steel material, andthe absorber sheath 500 can comprise a plastic material, a PVC material,an elastomer material, a 70A Shore hardness medical grade siliconerubber material, or a heat shrink tubing material.

In one embodiment, the absorber sheath 500 may be heat shrunk onto anoutside diameter of the flow tube 100. In another embodiment, as shownin FIG. 15, the absorber sheath 500 is adhered to the flow tube 100 withan absorber adhesive 510. In another embodiment, as shown in FIG. 15,the absorber sheath 500 is adhered to the flow tube 100 by insertmolding the absorber sheath around the flow tube 100. The absorberadhesive 510 can be acoustically transparent. In some embodiments, it ispreferable that the absorber adhesive 510 forms a flexible bond with theflow tube 100. In other embodiments, it is preferable that the absorberadhesive 510 forms a rigid bond with the flow tube 100. In someexamples, the absorber adhesive 510 can be a similar or the sameadhesive as the transducer adhesive 156.

The material of the absorber may be one of any polymers or elastomers,such as polyvinylchloride, silicone rubber, and the like. In oneembodiment, the material of the absorber may be flexible in nature andhave a lower durometer than that of the flow tube. By providing anabsorber having a different and lower durometer than that of the flowtube, the vibrations are maintained within the absorber, rather thanpassed into the flow tube. At the interface of the absorber and the flowtube is a boundary, and the behavior of energy at the boundary hasessentially two useable factors: reflection and transmission/refraction.The reflected and transmitted waves will obey Snell's Law.

With continued reference to FIG. 15, a fitting adhesive 186 ispreferably used to bond the flow tube 100 to the end fittings 185, suchas inlet fitting 180 and outlet fitting 190. Fitting adhesive 186 isprovided such that energy from the transducers 155, such as piezoelements 150, 151 is minimized across the Fitting-Tube Transmission Zone158, as shown by arrow T1. In certain configurations, energy from thetransducers 155 is not transmitted across the Fitting-Tube TransmissionZone 158. The fitting adhesive 186 dampens the energy transfer acrossthe Fitting-Tube Interface Zone 158 and maximizes losses at theFitting-Tube Transmission Zone 158. Preferably, the fitting adhesive 186dampens out of phase and/or rogue vibrations induced in the end fittings180, 190 by the transmission of sound energy between the first andsecond piezo elements 150, 151 and the end fittings 180, 190.Preferably, the fitting adhesive 186 is a low viscous, medical gradeadhesive, able to flow via capillary action into fill gaps, althoughother adhesives are also envisaged. In the Fitting-Tube TransmissionZone 158, an air gap between the outside diameter and the flow tube 100and the end fittings 180,190 may be desirable as this may reduce orprevent out of phase and/or rogue energy transmission which interfereswith the main signal to be detected by the microprocessor.

However, regardless of the configuration of the Fitting-TubeTransmission Zone 158, it may be desirable that the sidewall 111 of theflow tube 100 is in minimal contact with the end fittings 180, 190.Rather, it is desired that the end faces 113 of the flow tube 100 areprovided in contact with the end receiving face 117 of each of the endfittings 180, 190 as maximum transmission of energy is to occur from endface 113 to end receiving face 117 across End-Face Transmission Zone T2.During assembly this is accomplished by application of a longitudinalbiasing force on flow tube 100 in a direction toward the end fittings180, 190 as fitting adhesive 186 permanently bonds the flow tube 100 andthe end fittings 180, 190. Preferably, the fitting adhesive 186maintains its desirable properties after sterilization.

In one embodiment, it is desired that fitting adhesive 186 fills thecavity between the flow tube 100 and the end fittings 185 via capillaryaction providing a low flex modulus to attenuate acoustic coupling.Previous attempts to minimize energy transmission have involved the useof conventional O-rings, however, the use of O-rings is not possible ingaps which are less than 0.005″, such as the present gap between theflow tube 100 and the end fitting 185.

In order to optimize the capillary transmission of the fitting adhesive186, the fitting 185, such as either or both of the inlet fitting 180 orthe outlet fitting 190, may define an orifice having a conical interiorprofile and an adjacent shoulder having a matching size and orientationto match a received end of the flow tube 100 therein.

With specific reference to FIGS. 15, 16, and 18, inlet fitting 180 has adistal orifice 171 adapted to receive a proximal portion of the flowtube 100 therein. The distal orifice 171 defines an obconic or conicalorifice 172 having an abutting shoulder 175. Both the distal orifice 171and the abutting shoulder 175 have a matching size and orientation tomatch an end of the flow tube 100 which is receivable therein. Theconical orifice 172 is sized for insertion of either end of the flowtube therein, such that the distal orifice 171 of the inlet fitting 180is coaxial and concentric with the lumen of the flow tube 100, and suchthat the end of the flow tube 100 abuts the abutting shoulder 175. Theobconic or conical orifice 172 has a distal taper section 174 designedto allow capillary action to draw fitting adhesive 186 into the voidbetween the exterior of the flow tube 100 and the interior surface ofthe conical orifice 172 during assembly. In one embodiment, the conicalorifice 172 includes a proximal taper section 177 which creates a gapbetween the exterior surface of the flow tube 100 proximal to the distalend which does not fill with fitting adhesive 186 and provides an airgap, as shown in FIG. 15. The distal orifice 171 may be tapered andterminate at an end which is opposite the abutting shoulder 175 toengage the lumen of the flow tube 100. The distal orifice 171 of theinlet fitting 180 may be tapered and terminate at an end which isopposite the abutting shoulder 175 to engage a Luer type fitting. Incertain embodiments the distal orifice 171 is conical. In otherembodiments the distal orifice is obconic. In certain embodiments, thedistal orifice 171 includes a two-part taper having an intermediateshoulder 173 between the proximal taper section 177 and the distal tapersection 174. In other embodiments, the intermediate shoulder 173 isdisposed approximately half-way along the length of the distal orifice171. In another embodiment, the taper between the intermediate shoulder173 and the abutting shoulder 175 is such that tube 100 press fits withminimal to no air in this cavity and is not in contact with surface 175.

With specific reference to FIGS. 15, 17, and 19, outlet fitting 190 hasa proximal orifice 191 adapted to receive a distal portion of the flowtube 100 therein. The proximal orifice 191 defines an obconic or conicalorifice 197 having an abutting shoulder 195. Both the proximal orifice191 and the abutting shoulder 195 have a matching size and orientationto match an end of the flow tube 100 which is receivable therein. Theconical orifice 197 is sized for insertion of either end of the flowtube therein, such that the proximal orifice 191 of the outlet fitting190 is coaxial and concentric with the lumen of the flow tube 100, andsuch that the end of the flow tube 100 abuts the abutting shoulder 195.The obconic or conical orifice 197 has a proximal taper section 194designed to allow capillary action to draw fitting adhesive 186 into thevoid between the exterior of the flow tube 100 and the interior surfaceof the conical orifice 197 during assembly. In one embodiment, theconical orifice 197 includes a distal taper section 192 which creates agap between the exterior surface of the flow tube 100 distal to theproximal end which does not fill with fitting adhesive 186 and providesan air gap, as shown in FIG. 15. The proximal orifice 191 may be taperedand terminate at an end which is opposite the abutting shoulder 195 toengage the lumen of the flow tube 100. In certain embodiments theproximal orifice 191 is conical. In other embodiments the proximalorifice 191 is obconic. In certain embodiments, the proximal orifice 191includes a two-part taper having an intermediate shoulder 193 betweenthe proximal taper section 194 and the distal taper section 192. Inother embodiments, the intermediate shoulder 193 is disposedapproximately half-way along the length of the proximal orifice 191. Inanother embodiment, the taper between intermediate shoulder 193 andabutting shoulder 195 is such that tube 100 press fits with minimal tono air in this cavity and is not in contact with surface 195.

As shown by the progression of FIGS. 20A through 20D, the end fittings180, 190 may be adhered to the flow tube 100 with a fitting adhesive186. In the case of the inlet fitting 180, the fitting adhesive is drawinto the distal taper section 174 by capillary action. In the case ofthe outlet fitting 190, the fitting adhesive is drawn into the proximaltaper section 194 by capillary action. In one embodiment, the endfittings 180, 190 may be adhered to the flow tube 100 prior to theadhesion or other attachment of the absorber sheath 500 to the flow tube100.

In another embodiment, as shown in FIGS. 21A-D, the absorber sheath 500can be adhered to the flow tube 100 with an absorber adhesive 510. Theabsorber adhesive 510 can be acoustically transparent. In someembodiments, it is preferable that the absorber adhesive 510 forms aflexible bond with the flow tube 100. In other embodiments, it ispreferable that the absorber adhesive 510 forms a rigid bond with theflow tube 100. In some examples, the absorber adhesive 510 can be asimilar to or the same adhesive as the fitting adhesive 186 or thetransducer adhesive 156. As shown by the progression of FIGS. 21Athrough 21D, the absorber sheath 500 can be adhered to the flow tube 100with the absorber adhesive 510 before the end fittings 180, 190 areadhered to the flow tube 100.

While this disclosure has been described as having exemplary designs,the present disclosure can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the disclosure using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this disclosure pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A flow sensor sub-assembly for sensing flow of afluidic medicament comprising: a flow tube assembly through which saidmedicament flows having: a flow tube having a lumen, an outsidediameter, a first end, and a second end; an inlet fitting sized forinsertion of either end of said flow tube; an outlet fitting sized forinsertion of either end of said flow tube; and a first transducerarranged at the inlet fitting at an upstream position of the flow tubeassembly and a second transducer arranged at the outlet fitting at adownstream position of the flow tube assembly, such that the firsttransducer is spaced apart from one of the first end and the second endof the flow tube in a direction upstream thereof and the secondtransducer is spaced apart from the other of the first end and thesecond end of the flow tube in a direction downstream thereof.
 2. Theflow sensor sub-assembly according to claim 1, wherein the firsttransducer is a first piezo element and the second transducer is asecond piezo element.
 3. The flow sensor sub-assembly according to claim1, wherein the inlet fitting includes a conical orifice with a shoulder,said shoulder having a matching size and orientation to match an end ofsaid flow tube, wherein said conical orifice is sized for insertion ofeither end of said flow tube, such that an internal passage of saidinlet fitting is coaxial and concentric with said lumen and said end ofsaid flow tube abuts said shoulder.
 4. The flow sensor sub-assemblyaccording to claim 3, wherein the outlet fitting includes a conicalorifice with a shoulder, said shoulder having a matching size andorientation to match an end of said flow tube, wherein said conicalorifice is sized for insertion of either end of said flow tube, suchthat an internal passage of said outlet fitting is coaxial andconcentric with said lumen and said end of said flow tube abuts saidshoulder.
 5. The flow sensor sub-assembly according to claim 4, whereineach of said conical orifices has an inner diameter and a taper toengage the outside diameter of said flow tube thereby allowing capillaryinsertion of an adhesive during assembly
 6. The flow sensor sub-assemblyaccording to claim 1, further comprising an absorber sheath encirclingsaid flow tube, wherein said absorber sheath is comprised of a materialdifferent than said flow tube.
 7. The flow sensor sub-assembly accordingto claim 6, wherein said absorber sheath is heat shrunk onto saidoutside diameter of said flow tube.
 8. The flow sensor sub-assemblyaccording to claim 6, wherein said absorber sheath is adhered to saidflow tube.
 9. The flow sensor sub-assembly according to claim 1, whereinsaid first transducer and said second transducer are annular in shapeand encircle the each respective fitting at each respective mountingpoint.
 10. The flow sensor sub-assembly according to claim 1, whereinsaid flow tube assembly is contained within a flow sensor housing havinga circuit engaged to said first transducer and said second transducer,wherein said flow sensor housing is coupled to a flow sensor base whichcontains a microprocessor and said circuit includes connecting pins forproviding said electrical signal from said flow sensor sub-assembly tosaid microprocessor within said flow sensor base, wherein said flowsensor sub-assembly is disposed after said flow sensor sub-assembly isused to sense the flow of at least one fluidic medicament, and whereinthe flow sensor base is used with a different flow sensor sub-assembly.11. The flow sensor sub-assembly according to claim 2, wherein saidinternal passage of said inlet fitting is tapered and terminates at anend opposite said shoulder to engage a luer type fitting.
 12. The flowsensor sub-assembly according to claim 2, wherein said internal passageof said inlet fitting is tapered and terminates with an obconic sectionat an end opposite said shoulder.
 13. The flow sensor sub-assemblyaccording to claim 4, wherein said conical orifices of said inletfitting and said outlet fitting are two-part tapers having anintermediate shoulder approximately half-way along the length of saidtaper.
 14. A method of assembly of a flow sensor sub-assembly forsensing flow of a fluidic medicament comprising: providing a flow tubehaving a lumen, an outside diameter, a first end, and a second end;providing an inlet fitting; inserting an end of said flow tube into saidinlet fitting; providing an outlet fitting; inserting an opposite end ofsaid flow tube into said outlet fitting; providing a first transducer atsaid inlet fitting at an upstream position of the flow tube assemblysuch that the first transducer is spaced apart from the end of said flowtube in a direction upstream thereof; and providing a second transducerat said outlet fitting at a downstream position of the flow tubeassembly such that the second transducer is spaced apart from theopposite end of said flow tube in a direction downstream thereof. 15.The method according to claim 14, wherein the inlet fitting includes aconical orifice with a shoulder, said shoulder having a matching sizeand orientation to match an end of said flow tube, wherein said outletfitting includes a conical orifice with a shoulder, said shoulder havinga matching size and orientation to match an end of said flow tube, themethod further comprising: inserting said end of said flow tube intosaid inlet fitting conical orifice until the end of said flow tube abutssaid shoulder of said inlet fitting; and inserting said opposite end ofsaid flow tube into said outlet fitting conical orifice until saidopposite end of said flow tube abuts said shoulder of said outletfitting.
 16. The method according to claim 14, further comprising thestep of: inserting said flow tube into an absorber sheath encirclingsaid flow tube, wherein said absorber sheath is comprised of a materialdifferent than said flow tube.
 17. The method according to claim 14,further comprising the steps of: inserting said flow tube into anabsorber sheath encircling said flow tube; and heating said absorbersheath to shrink said absorber sheath onto said outside diameter of saidflow tube.
 18. The method according to claim 16, wherein said absorbersheath is adhered to said flow tube.
 19. The method according to claim14, further comprising the steps of: inserting said inlet fitting intoan opening in said first transducer; and inserting said outlet fittinginto an opening in said second transducer.
 20. The method according toclaim 14, further comprising the step of: bonding a flexible tubing toan opposite end of an internal passage of either said inlet fitting orsaid outlet fitting.